Automatic telephone-exchange.



PATENTED AUG. 7, 1906.

0. D. BNOG'HS. .AUTOMATIC TELEPHONE EXGHANGB.

APPL IOATION FILED 001216, 1905.

wound ringing-relay, and hence this relay is UNTED srArEsfgPArn'Nr orrron.

CLAUDE l). ENOCI-IS, OF LA CROSSE, WISCONSIN, ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

l'o (all wiz/om, ifm/fm won/cern:

Be it known that LCLAUDE D. ENooHs, a citizen of the United States, residing at La Crosse, in the county of La Crosse and State ol Wisconsin, have invented a certain new and useful Improvement in Automatic Telephone- Exchanges, of which the following is a full, clear, concise, and exact description.

My invention relates to a telephone system; and its object is to provide an arrangement of apparatus and circuits by which two magnets included in said circuit may be actuated simultaneously, or one of the magnets may be actuated independently of the other.

My invent-ion when used in connection with an automatic telephone system provides a circuit in which only non-pol arized magnets are used and in which few contacts are employed, thus providing a cheap and simple system by which the selective switching of any two subscribers instruments into connection with each other. may be readily accomplished.

In my invention, when employed in connection with an automatic exchange, I employ the usual apparatus at Aa subscribers station, including an interrupter and the usual selector at the central ollice.

In theA circuitl of my invention two doublewound non-polarized relays are em yloyed, one for controlling the selecting mec anism and one for controlling the ringingenerator, the relays being' so connected in t ie circuit that one winding of each is between the battery Vand the line. When the calling -subscriber after removing his receiver from the hook operates his intcrrupter, the 'metallic circuit through the relays is interrupted, with the-result that the ringing-relay, being'di'l'erentially wound, is not operated, While the seli-icting-relay, being cumulatively wound, is actuated. .T he selecting-relayA responds to the interruptionsand through the medium of a local circuit, including a stepping and a retainingl magnet, operates the selector'. kIlVlien v the calling party operates his ringing-key, the

metallic circuit is opened and one side of this telephone-line is grounded, a circuit being thus v.completed over said line through the central battery to groundg This circuit includes onlyT one winding of the differentially- Specification of I.ettersv Patent. Application-tiled October 16,1905. Serial No. 282,986.

Patented Aug. 7,1906.

energized and operates to connect the selector-brushes to the ringing-generator or other source of Iringing-current.

I will describe my invention more particularly by reference to the accompanying-drawing, which is a circuit-diagram of two telephone-lines extending from their respective subscribers7 stations to a central ol'ice, where each line 1s equipped with apparatus for per-A forming the various switching operations required in making connection with .any other line of the exchange7 it being understood that each line of the exchange has an equipment similar to that illustrated in the drawing.

The system shown is arranged on the central-battery plan both for signaling and talking. -Each line has, as usual, two main conductors or line-wires 1 2, and the central battery b is connected in a bridge of the circuit, one pole of the battery being grounded in accordance with the usual practice.

ed inthe bridge, the one, a, for ringing, and the other, c, -for selecting, the relays being so connected in circuit that one winding of each is between the battery and the line. The linewires 1 and Z terminate in the contact-brushes 2, res ectvel carried b a' selector-arm jEliivch linie) has a 5air of termlinals h h2 on eacjh selector, with/t 'ch the movable contacts of the selector-arm may make connection.

The rotating arm f is arranged to be advanced by a stepping-magnet e and to be held in its advanced position by a retaining-magnet d,'saicl magnets being connected in a local circuit 5 6, which is controlled by the selecting-relay c, said relay in turn being controlled by the switching mechanism at the subscribers station.

rIhe contact-brushes f f2 of the selector'- arm f are arranged to trailover the pairs of stationary line-terminals h 7L, arranged in a circle about its axis. The contact-brushf ofthe selector-arm is arranged to be connected by a conductor 3 with the line conductor 1, of which it forms an extension, said con- Two doul ble-wound non-polarized relays are connectductor 3 being conductively divided .by a condenser y and normally closed at contacts of relay a. Similarly, the contact-brush f2 of the selector-arm isv arranged to be connected with line conductor 2 by extensions 4l, 4a, and 4v of said conductor, said extension 4a IOO also being normallyv closed at contacts of relay a and conductively divided by a condenser 'y'.

The ringing-relay a is differentially wound andthe Selecting-relayc cumulatively Wound, so that when the metallic circuit is closed the relay a is not operated, while the relay c is actuated to close the local circuit 6, includngthe battery b, thestepping-magnet e, and the retaining-magnet d.

Of course it is understood that the stepping-arm{ may be mounted radially upon a ratchet-w ieelfs, which is suitably mounted to rotate. The stepping-magnet e is provided with an armature e', which carries a pawl e2, pivoted on its end and adapted to engage the teeth of the ratchet-wheelf3. The armature is pivoted at g and is normally held away from the magnet by the spring g. When the armature is attracted, the pawl e2 is released from the post e3 and is drawn by a whee fsf into engagement with the toothed This advances the ratchet-wheel, and the selector-arm is carried thereby one step. The ratchet-wheelf3 is arranged to be held at any point to which it may be advanced bya retaining-pawl d2, forming an extension of the armature d of the retainingmagnet d. When the armature d is in its normal unattracted position, the retainingpawl d2 is lout of engagement with the-ratchet- Avheel; but when said armature is attracted the retaining-paw] is held against the ratchetwheel. The co eration of both the -stepping-magnet an the retaining-magnet is necessary to bring about lthe rotation of the selector-arm.

The retaining-magnet d is arranged to act sluggishly in releasing by means of a non-inductive shunt d4, while the stepping-magnet is adapted to respond quickly to a cessation of current. Since these two magnets d and e are in series in the local circuit 5 6, when an sprin -intermittent or pulsating. current is passed through the circuit the armature d will be continuously attracted, whilearniature e will be vibrated. The result is a step-by-step advance of the ratchet-wheel and the selector-arm carried thereby, t'henumber of steps of advance being determined by the number of impulses of current appliedto the magnets.

The means for actuating the irelay c to cause the production of these intermittent currents is an interrupter n at the subscribers station, the o eration of which is hereinafter describe he ringing-generator G is included in a circuit 7 8, normally open at the contacts of relay a and adapted to be closed by the operation of said relay, as hereinafter described.

As before stated, the advance of the selector-arm f at the central station is dependenti upon the intermittent closing ofthe local circuit 5 6, which is controlled at a normally` open contact of the selecting-relay c. To procludes, in additon to the usual telephone apparatus, an interrupter which, when operated, Will intermittently open and close the metallic circuit, and hence the' relay c will be intermittently excited. Any form of interrupter for making and breaking the circuit may be used. That which I have chosen to illustrate comprises a toothed wheel n', arranged to actuate a movable spring o as the teeth of the wheel pass in succession'undei said spring. A ratchet-Wheel n2 is mounted to rotate with the toothed wheel n. A controller-arm n3, which may b e moved forward looselyv upon the axis of the wheel against the tension of a coiled spring n", carries a pawl ns, which, as the controller-arm is returned by the spring after its advance, engages the ratchet-wheel to carry the same and the toothed wheel n around with it, whereby the spring o is actuated to close and open the circuit at contact n". The number of times the contact n is closed and opened depends upon the distance to which the controller-arm is advanced, which distance is regulated by the calling subscriber to corre-- spend with. the terminal on the selectorto which the called subscriber is connected.

The operation ofthe systexnmay now be understood. When a subscriber at station A, for example, desires to call thegsubscriber at station B, he takes his telephone-receiver from its hook, whereby a metallic ,circuit is completed, which maybe traced as follows: from the positive terminal of the battery b through the conductor 9, including a winding of relays' c and a, conductor 4, hne 2, the subscribers telephone set, line 1, conductor 10, including the other windings of relays a and c" to the negative terminal ot battery b..

IOC

the interruptions, and thus causes corre-/ 12o spending intermittent impulses to be transmitted over the local circuit 5 6. The stepping-magnet e is thus caused to intermittently attract its armature and so to advance the selector-arm step by step. T he selector-arm is held in its advanced position by the retaining-magnet d, which being made sluggish does not follow the pulsations of thecurrent, but keeps its armature steadily attracted. When the operation of they vss interr-u'pter a ceases, the metallic circuit is closed at the contact a7, so that while the subscribers receiver is odf its hook the relay c is actuated, the local circuit 5 6 closed, and the retaining-pand cl2 in engagement with the teeth of the wheel 3. The subscriber at A having operated is interrupter n, so that the selector-arm f, carrying the extensions of his line, is in engagement with the terminals i' 712, to which the subscribers line at station B is connected, the telephoneline of the subscriber at'A is placed in connection with thc line of subscriber at station B. The ist step is to ring up the sub'- scriber at station B. To do this, the subscriber at station A operates his ringing-key then -first grounding the line l and then opening the metallic circuit. to ground one line before opening the circuit in order that the contact OfseIectiDg-relay c may be held closed during the switching operation and further actuation of the selectorarni thereby prevented. A circuit is then closed from ground at station A through line l, conductor l0, including a winding of relays c and c, battery b, to ground at the cen-i tral station. Since this circuit includes only one winding of the dii'lerential relay a, said ielwapy, as well as relay c, is energized. The relay (i operates to clc se its front contacts,.and thus to connect the selector-brushes f f2 to the ringing-generator G or other source of ringing-current through lines 7 and 8., respcctiveiy. Current then passes to contacts li. ifl et the called snbscribers line out to the called station through the bridge containing the signal-bell. As soon as the' subscriber at A ceases to operate his ringingkcy his lineis again closed at the back contacts of the relay a, scriber answers, a talking-circuit between the two stations is estab'ished. A subscriber ena party-line can also signal and converse with any other subscr'ber on the same line. 'lhe operation of selecting and ringing is exactly the same as that above described, since the calling-line is also connected by conductors la and 2 with terminals on the selector. In calling andther substation'on the same line the calling subscriber rings in accordance with the code-number signal of ihc staion wanted.

"l claiin-e l. ln an automatic telephone-exchange, the combination with a telephone-line extending l`roin a substation to a ceiitial-oilice` battery, on(` pole of which is grounded, oi" a selecting-relay r .onnccted insaid circuit, selecting mechanism controlled by said relay, a dill'ercnlhilly-wound ringing-relay having its wii'idings also included in said circuit with oniI winding on cithcr side oi said battery, ringing mechanism controlled bysaid ringing. relay, and switching mechanism at thesnbstation for closing the circuit ol the line and It is necessary and when the called `sub- .for grounding one side of the line, whereby said selecting-relay may be independently actuated 0r both' relays simultaneously aetuated, substantially as described.

2.' 4ln an automatic telephone-exchange, the combination with a telephone-line, of a bridge ot the line at the central office including a battery one pole of which is grounded, two double-wound relays having their windings included in said bridge, each relay having one winding on either side ot said battery and one magnet being cuinulatively wound, and the other differentially wound, selecting lmechanism controlled by said cumulativel y- Wound relay, a ringing-generator controlled by said differentially-wound relay, switching mechanism at the subsci'ibers stat-ion whereby the metallic circuit of' the line may be closed and the cuinulatively-wound relay independently actuated to operate the selecting mechanism, and additional switching means whereby one line may he grounded andthe relays simultaneously actuated, the differentially-wound relay teactuate the ringing mechanism, while the other'relay controls the selecting mechanism, substantially `as described. i

3. In an automatic telephlbne-excliange,

,the combination with al telephone-line, of a selector having a selector-arm carrying a air of contact-brushes constituting termina s of said line, and stationary contact-terminals of other lines, a local circuit including a magnet for o erating mechanism by which said contactrushes are trailed across said terminals, a circuit including a ringing-generator, two double-wound relays in bridge of the telehone-lines, the one for controlling the seecting-circuit being cumulatively wound, and the one forcontrolling the ringing-circuit dierentially wound, said relays being connected in circuit with one winding of each between the battery and the line, and means at the subscribers station for controlling the operation of said relays.

4. In an automatic telephone-exchange, the combination with` a telephone-line, of a selector individual to the `line having a p'air of movable contact-brushesand stationaryv contact-terminals, a normally open local circuit including a stepping-magnet and a retaining-magnet for operating mechanism by which said contact-brushes are trailed across said terminals, a normally open circuit including a ringing generator, two doublewound. relays, one for controlling the selecting-circuit and the other the ringing-circuit, said relays being connected in bridge of'v the telephone-circuit with one winding et cach lbetween the battery and the line, and means at the subscribers station for controlling the operation et said relays;-

5. In an automatic telephone-exclrange,

- the combination with a selector lia-ving a movable centact-brush adapted to forni the ter- IIO minal of a calling-line, stationary contacts of o'ther lines with which said movable brush is adapted to be engaged, a local selecting-circuit including a magnet for operating mechanism by which said contact-brush is trailed across said terminals, a ringingcircuit including a ringing-generator, a selecting-relay and a ringing-relay connected in series with the central battery in bridge of t'he telephonelines for controllingr the selecting-circuit and the ringing-circuit respectively, said relays each having double windings, said selectingrelay being cumulatively wound and said ringing-relay differentially wound with one winding of each relay between the battery and theline, an interrupter at the subscribers station for making and breaking the metallic circuit through said relays by which the selecting-relay is energized to move the selector-brush to the terminals of the called subscriber', anda ringing-key at the subscribers Station by means of which a grounded returncircuit is closed including only one winding of the dill'erentially-woundringing-relay, Whereby said relay is energized to connect the ringing-generator to the circuit oi the called subscriber, substantially as described.

6. ln an automatic telephone-exchange, the combination with a selector having a pair of movable contact-brushes adapted to form terminals of a calling-line, stationary contacts of other lines with which said movable brushes a 'e adapted to be engaged, a local selecting-circuit including a stepping-magnet and a retaining-magnet for operating mechu saaioi anism\ by which said contact-brush'is trailed acrosssaid terminals, a ringing-generator, a selecting-relay and a ringing-relay connected in series with the battery one pole of which is grounded, in bridge of the telephone-lines for controlling the selecting-circuit and the ringing-generator respectively, said relays each having double windings, the selecting-relay being cumulatively wound and the ringingrelay differentially wound with one winding of each relay between the battery and each line, aninterrupter at the subscribers station for making and breaking the metallic circuit through said relays by which the selecting-relay is intermittently energized, thereby opening and closing the selectingcircuit so that the magnets in said circuit advance the selector-brushes to the terminals of the called subscriber, and a ringing-key at the subscribers station by means of which the metallic circuit is opened and a grounded circuit is closedincluding only one winding of each of said relays, whereby the ringing-relay is energized to connect the ringing-generator to the circuit of' the called subscriber and the selecting-relay is energized to close the selecting-circuit, whereby the retainingmagnet holds the selector-arm in its advance position, substantially as described.

ln witness whereof l hereunto subscribe my name this 26th day of July, A. D. 1905.-

CLAUDE D. ENOCHS. Witnesses:

RUTH WARREN, OLGA JENSEN. 

